Flexible metal compounds



March 18, 1952 J. F. JOY 2,589,394

FLEXIBLE METAL COMPOUNDS Filed June 15, 1946 Fig. 1.

M 'ENTOR.

Joseph F Joy.

AT RNE Y.

Patented Mar. 18, 1952 FLEXIBLE METAL COMPOUNDS Joseph F. Joy,Pittsburgh, Pa., assignor to Joy Manufacturing Company, Pittsburgh, Pa.,a corporation of Pennsylvania Application June 15, 1946, Serial No.677,064

3 Claims.

My invention relates to flexible metal compounds, and the principalobject of my invention is to provide new and improved compounds of thecharacter described, and new and improved processes for producing same.

In the drawing accompanying this specification, and forming a part ofthis application, I have shown, for purposes of illustration, anembodiment which my invention may assume, and in this drawing:

Fig. l is a perspective view of a sheet of material embodying theinvention.

Fig. 2 is an enlarged longitudinal sectional view correspondinggenerally to the line 2--2 of Fig. 1.

Fig. 3 is an enlarged fragmentary sectional view illustrating theembodiment of the invention.

Fig. 4 is a sectional view similar to Fig. 3, but showing the materialunder tension.

Fig. 5 is an enlarged fragmentary sectional view illustrating a metalparticle as it is contained within the flexible body.

Flexible metal compounds forming the subject matter of this inventionhave a multitude of uses and applications, and are particularly usefulin apparatus wherein fluids are employed for the fulfillment of certainfunctions. Such flexible metal compounds have particular application asseals for pistons, rod packing, and rotary shaft seals wherein thesealing means should be impervious to passage of fluid therethrough, yetbe sufficiently resilient to seal against fluid passage therearound.However, it is to be understood that my invention is not limited only tothose applications herein disclosed.

I am aware of the fact that metallic particles have been used heretoforein various quantities for the so-called loading of rubber compounds, butI have found that merely loading of rubber with metal particles is notsufficient, since under certain conditions, such as when the compound isplaced under tension, there is a tendency of the rubber to pull awayfrom the individual metal particles, thus leaving countless voids in thecompound which defeat its purpose as a sealing means, and also whichlead to an early physical destruction of the compound. My inventioncontemplates bonding of each individual metal particle to the flexiblecarrier material, so that, for instance under tension, the carriermaterial will stretch between particles, instead of stretching as aflexible body generally. Thus when tension is removed, each individualparticle will still have bonded contact with the adjoining carriermaterial, and the destructive voids hereinbefore mentioned arecompletely eliminated. In view of this, it will be appreciated that myimproved compound has physical properties superior to those possessed bycompounds disclosed by prior art.

The metal to be used in the compound is dependent largely on the use towhich the compound is put. For example, where antifriction and heatconducting properties are of prime importance, a copper bearing metalmay be preferred. On the other hand, where weight is of primeimportance, such as is the case in balloon linings, a metal such asaluminum or magnesium may be preferred.

In the compound hereindisclosed, the metal is the preponderantingredient, and it is introduced into the compound preferably in theform of finely powdered dust, the dust particles being held in closelyassociated relation by means of a flexible binder. It will beappreciated that in such compound, the metal provides antifriction andfluid sealing qualities, and the binder provides the flexible qualities.By reason of the preponderant metal content, particularly with respectto certain types of metal, the compound has relatively high thermalconducting properties, and this is of importance in cases of seals andthe like.

As an example, my compound has been successfully used for forming thesealing lips of piston and rod packings and of rotary shaft sealsemployed for confining oil and gas within the recoil mechanisms of heavyguns. In modern mechanisms of this type, fluid pressures as great asthree thousand (3000) pounds per square inch are common, and pistonspeeds exceeding fifty (50) feet per second frequently occur. Theseelements of pressure and piston speed contribute to gun carriagelightness and rapidity of gun firing capacity and are therefore highlydesirable. Yet, the achievement of such pressures and speeds imposesevere operating conditions upon the sealing members. Since theslightest loss of fluid may impair the efficiency of, or totally renderinoperative, such mechanisms, the sealing action should be as nearlyabsolute as is possible.

Operation under heavy pressures and high piston speeds causes generationof considerable heat because of frictional rubbing contact between therelatively moving parts. Therefore, it is highly desirable to conductheat away from the rubbing surfaces and dissipate it in the surroundingatmosphere, and my compound, be

cause of its high metallic content, is extremely suitable for thispurpose.

In the drawing, my compound has been shown in sheet form, such as thesheet Ill, although it will be appreciated that the compound may beformed to any other shape, and may be molded or otherwise shaped to anydesired finished form.

The flexible binder in the illustration shown in the drawings is rubber,as shown at H, although any other suitable flexible or resilientmaterial may be used which is capable of having metal bonded to it insuch manner as to provide the desirable qualities of the rubber-metalcombination herein disclosed. Since seals, at least in certain cases,are required to resist deterioration caused by contact with oil andother materials, it has been found preferable, although not essential,to use a flexible binder that will resist such deterioration. Syntheticrubbers, at least of certain types now commercially available, have beenfound to suit such purpose admirably.

The metal, represented by the numeral l2 in the drawings, may take anyform, this being dependent largely upon conditions which are to befulfilled. Therefore, it will be appreciated that the size and shape ofthe metal particles may be varied without departing from the spirit ofmy invention.

In addition to the metal particles and the flexible binder, certainother materials may be required to complete the compound, thesematerials varying in chemical composition and proportion depending uponthe flexible binder used and the conditions to be fulfilled.

As an illustrative example of the ingredients which may be used inproducing my flexible metal compound, I offer the following formula andprocess:

mentioned ingredients comprises thoroughly stirring into the metallicpowder approximately fifty (50) parts by weight of a bonding agent forthe purpose of coating the surface of each metallic particle so as tocause the final compound to become a closely bonded flexible metalproduct.

As an example of a suitable bonding agent, I have used a commerciallyavailable chlorinated rubber base cement sold under the trade name ofTy-Ply. The composition of Ty-Ply is disclosed in U. S. Patent No.2,259,190, on page 1 at lines 10 to 14, as a liquid coating compositioncomprising chlorinated rubber capable of curing to a relativelynon-thermoplastic adhesive product on drying and heating, and isspecifically claimed (claim. 1) as a cement consisting essentially ofrubber chloride, a volatile solvent, sulfur, and a minor amount of anorganic accelerator for the vulcanization of rubber. However, it will beappreciated that other chlorinated rubber adhesives may be used in thecarrying out of my invention.

The mixture of metal dust and bonding agent should be subjected tosufflcient heat to drive off the moisture until the mixture takes acrust-like appearance, at which time it is ready for milling n 1Ingredients Metallic powder, preferably particle sizes ranging be tween8 and 20 microns 140. 0 Neoprene G RM" (or Neoprene GN as it was iormerly designated) 54. 0 Retarder W (Salicylic Aci 2. 0 Magnesia Oxid 2.0Neozonc D i .6 Zinc Oxide l. 5 Cumar 2. 6 gil (Circo Light Process) crmTotal Parts 207. 7

Viscosity 100 F 150-160 Flash ASTM open cup 325-330 Fire 370-380 Pourtest ASTM 30 F. Max.

NPA color 2 Demulsibility Good Conradson carbon .02

Neutralization No. Neutral Neozone is basically a napthylamine used asan antioxidant and is specifically known as phenyl-beta-napthylamine.

The preferable method of processing the aforeinto the other ingredients.

The remainder of the mixture may be prepared by milling the neopreneGR-M just the same as when it is to be used for the processing ofsynthetic rubber parts, adding the retarder W as the neoprene stockwarms up. The magnesia oxide, neozone D," zinc oxide, cumar, Circo lightprocess oil, and acrin may be added to the neoprene GR-M, and themilling may be continued until the stock is well mixed. This, accordingto the above proportions, will make 67.7 parts which is used to form theflexible binder for the final flexible metal compound.

The flexible binder may then be added to the coated metallic particles,and the mixture milled until thoroughly mixed. Thorough mixing may bedetermined by sheeting and cutting into strips, and examining the edgesof the strips for evidence of segregations of metal particles. When themetal particle dispersion is uniform, the mix is ready for molding andcuring or vulcanizing, which comprises applying heat at approximately307 F. for about twenty-five (25) minutes. The mix, prior tovulcanizing, is moldable, and gaskets, seals, packing and other productsmay be molded to any desired shape and form.

For certain purposes, such as for certain seals, I have usedcommercially available bronze powder as the metallic particles, andusing substantially the aforementioned proportions, the resultantproduct had the following physical properties:

Elongation per cent 250 Tensile strength to the square inch pounds 600Hardness (durometer test) do It will be appreciated that changes inmetal, or in other ingredients, or in proportions of ingredients withinlimits, will vary the physical properties of the compound withoutdeparting from the spirit of the invention.

Referring to Fig. 5 of the drawing, it will be seen that each metalparticle is provided with a coating 13 of bonding agent, which coatingis left after the mixture of metal dust and bonding agent has beensubjected to sufficient heat to drive off the moisture. Therefore, theentire exterior surface of each metal particle will have a good lastingbond with the adjoining flexible binder, such as the rubber shown. Thisbonding agent should not be confused with other coatings for themetallic particles, as taught by the prior art. Such coatings are onlyfor the purpose of preventing the metal particles from lumping orcoalescing, and in no manner do they provide for secure connectionbetween each metal particle and the adjoining flexible binder. Attentionis directed to Fig. 4 of the drawings, wherein the flexible compound isshown under tension. Comparison of this figure with the constructionshown in Fig. 3 will clearly show that the metal particles are securelyattached to the rubber, and the rubber stretches intermediate theparticles. This, at least in part, explains the very desirable physicalproperties obtainable with compounds made in accordance with myinvention. The term a rubber as used in this application is intended todesignate both natural and synthetic rubbers capable of beingvulcanized, and the term a vulcanized rubber and like terms to includesuch rubbers in a vulcanized condition.

From the foregoing, it will be apparent to those skilled in the art,that I have accomplished at least the principal object of my invention;and it also Will be apparent to those skilled in the art that theembodiments herein described may be variously changed and modified,without departing from the spirit of the invention, and that theinvention is capable of uses and has advantages not herein specificallydescribed; hence, it will be appreciated that the herein disclosedembodiment is illustrative only, and that my invention is not limitedthereto.

What I claim as new and desire to secure by Letters Patent is:

1. A flexible compound having relatively high thermal conductingproperties comprising a vulcanized rubber body, finely divided metallicparticles intimately dispersed throughout said body, and a film of avulcanized chlorinated rubber base cement coating said particles andfirmly bonding them to said body, said particles cumulativelyconstituting a preponderant portion by weight of said compound.

2. A flexible compound comprising a vulcanizizable mass of a rubber,having thickly dispersed therethrough and embedded therein metallicparticles coated with a chlorinated rubber adhesive, said mass and saidparticles integrated into a body by the vulcanization of said mass andthe coatings of said metallic particles, and said ch10- rinated rubberadhesive bonding the rubber to the metallic particles.

3. The method of making a flexible metallic product having relativelyhigh thermal conducting properties suitable for seals between relativelymoving contiguous elements which comprises wetting particles of a finelydivided mass of metallic particles with a chlorinated rubber basecement, evaporating the solvent from the cement, dispersing the treatedparticles throughout a vulcanizable rubber mass, in such proportionsthat the metal is a preponderant portion by Weight of the mixture, andvulcanizing the resulting mixture to form a strong integral flexiblemetallic product.

JOSEPH F. JOY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,438,735 Williams Dec. 12, 19222,084,784 Stahl June 22, 1937 2,286,260 Carter June 16, 1942 2,377,153Hunter May 2-9, 1945 OTHER REFERENCES The Duprene Manual, publishedAugust 1, 1934, by E. I. Du Pont 00., pages 43-44, 56.

India Rubber Journal, February 29, 1936, page 253.

Du Pont Rubber Chemical, published February 1943, by E. I. Du Pont 00.,pages 105-106, -76 and 21-22.

1. A FLEXIBLE COMPOUND HAVING RELATIVELY HIGH THERMAL CONDUCTING PROPERTIES COMPRISING A VULCANIZED RUBBER BODY, FINELY DIVIDED METALLIC PARTICLES INTIMATELY DISPERSED THROUGHOUT SAID BODY, AND A FILM OF A VULCANIZED CHLORINATED RUBBER BASE CEMENT COATING SAID PARTICLES AND FIRMLY BONDING THEM TO SAID BODY, SAID PARTICLES CUMULATIVELY CONSTITUTING A PREPONDERANT PORTION BY WEIGHT OF SAID COMPOUND. 